From knitted loop to crocheted stitch

In the past few posts I’ve considered different approaches to the graphic description of looped fabric structures. Although largely in abstract terms thus far, my intention is to apply relevant aspects of them to the analysis of specific objects that have themselves been the focus of other posts or are in the queue for such treatment.

Analytic terminology has been another perennial favorite here. The subject this time around is a formal international standard that both defines and illustrates structural details of knitted fabric in terms that are applicable to other forms of loopcraft, as well. The extent of that applicability will be tested with a comparison of plain knitting (stocking stitch) and plain crochet (slip stitch).

I had previously suggested that crochet could be seen as a handcraft equivalent to warp knitting, using terms taken from the International Standard ISO 4921:2000, Knitting — Basic concepts — Vocabulary. This “defines terms for basic knitting concepts” applicable both to hand and industrial knitting although many of the definitions are only used in the latter context. A related standard ISO 8388:1998, Knitted fabrics — Types — Vocabulary, more explicitly “defines terms for industrially produced machine knitted fabrics” but is relevant to hand knitted fabric nonetheless.

The vocabularies in both are useful when comparing other aspects of crochet and knitting since they accommodate both symmetrical and asymmetrical loops, and define the terms ‘loop’ and ‘stitch’ separately. Although these distinctions may not be necessary for the categorization of hand-knitted structures, the associated terms label different properties in crochet and are essential to its description.

The ISO vocabulary is based on the following differentiation of a loop, a knitted loop, and a stitch. A “loop of yarn” (a permitted alternative to the preferred term “kink of yarn”) is “a length of yarn that has been bent into a shape appropriate for its transformation into a weft-knitted or warp-knitted loop.” Three specimen forms are illustrated.

A “knitted loop” is then defined as “a kink of yarn that is intermeshed at its base.”

The one at the top is an “open loop,” defined as “a knitted loop in which the same thread enters and leaves the loop at opposite sides without crossing over itself” and noting that “the same applies to an open stitch.” The bottom right shows a “closed loop” — “a knitted loop at the base of which the thread crosses over itself” — and again “the same applies to a closed stitch.” The closed loop is also illustrated under its own heading but in neither instance are the two possible directions for the crossover labeled or even noted (‘S’ as shown here, or ‘Z’ as in a following illustration; both are explained in the preceding post).

Finally, a “stitch” is “a kink of yarn that is intermeshed at its base and at its top.”

This illustration shows a “reverse stitch,” also called a “back stitch” and is explicitly “not the same as a purl stitch” (which means slightly different things in hand and industrial knitting). There is a separate illustration of a “face stitch,” also called a “plain stitch” or a “stocking stitch.” The difference is that the face stitch is “so intermeshed in the fabric that its legs are situated over the top arc of the stitch formed in the same wale in the previous course.”

The terms wale and course correspond to the more familiar column and row but explicitly refer to sequences of stitches and not loops. It is also significant that the term “stitch” is not further specified as a knitted stitch and its definition includes a broad scope note.

“A stitch may be combined with a float, and different types of knitted loops and stitches may be combined in a unit of stitches or an arrangement of stitches.
≠ a knitted loop”

The named arrangements of stitches include a “binding-off course” defined as, “a new row of loops, each one transferred to the adjoining wale and forming a ladderproof chain of loops at the top end of a knitted article.”

The lateral repositioning of a knitted loop changes it from symmetrical to asymmetrical but it retains its basic structural identity. When the knitted loop in the adjoining wale is pulled through it, the initial loop is intermeshed at its base and top, thereby becoming a stitch. The ISO vocabulary doesn’t have a name for it but the definition of the binding-off course implies that it would be called a chain stitch.

The preceding illustration can be seen as a detail from the upper end of a piece of knitted fabric that could include additional lower courses of knitted stitches. There is also a type of crocheted fabric that consists of multiple courses of chain stitches identical to those in the binding-off course. This has the slip stitch structure illustrated in numerous previous posts and seen in this drawing taken from a description of a bootee in the collections of the National Museums of Scotland, by Audrey Henshall (also shown in earlier posts).

All documentation of this fabric prior to the 1820s describes it as ‘a species of knitting,’ with the word ‘crochet’ only used to designate the hook. It can also be seen as a form of knitted fabric according to the ISO definition. Nonetheless, it is now primarily associated with crochet. The vertical intermeshing of one course of chain stitches with another is the definitive attribute of its simplest form, variously termed plain crochet, slip stitch crochet, or single crochet (UK).

A bind-off course fashioned with knitting needles requires all of the knitted loops to be held on a needle until they are worked successively into chain stitches on the next pass. With a crochet hook, the knitted loops are taken onto the tool individually and immediately intermeshed into chain stitches. This is also the more practicable technique for working courses of chain stitches into crocheted fabric.

Regardless of how the fabric illustrated in the two preceding drawings can be produced, both show the same structural characteristics. The knitted loops all lean to the right, they are all open, and they are all worked into the back side of the preceding stitch (BLO). Their legs pass behind it, forming reverse stitches.

Another of the drawings of slip stitch crochet that’s already been used several times on this blog, by Annemarie Seiler-Baldinger, shows a different configuration. The knitted loops lean to the right here as well but they are closed (with a Z crossing). They are also worked into the back side of the preceding stitch but their legs pass in front of it, forming face stitches.

The correlation between the variant forms of this structure and the procedural aspects of their production as slip stitch crochet were discussed in depth in the preceding post, deferring a few relevant details for later consideration. One of them is the difference between face and reverse stitches. This correlates basically to whether the yarn is held in back or in front of the fabric, with the hook inserted into it from the front or back, while the loops and stitches are formed.

This maps directly into the colloquial knit and purl of hand knitting. However, the latter term is not widely recognized in crochet and the labeling of reverse stitches is a matter of recurring debate. Slip stitch crocheters commonly refer to them as ‘inverse slip stitches,’ which needn’t be taken any further for now. However, the concept of inverse does not scale as clearly into more complex crochet stitches.

One further property of a slip stitch can make the analysis of fabric produced with it more difficult than that of fabric made with the stocking stitch. In the latter, the initial loop will be open or closed and that property will be propagated into the stitch, and then retained in the fabric. With the slip stitch, a new loop that is worked into the front side of a stitch in the preceding course (FLO), applies a vertical force to the stitch that can reverse its open or closed characteristics.

The two-loops-in-one attribute of crochet makes it a compound structure and therefore nominally comparable to the one-loop-over-two compound knitting discussed here, and illustrated with this schematic drawing by Marianne Eriksson.

However, the mechanical dynamics of the intrinsically compound slip stitch and those of the stocking stitch whether compound or not, are fundamentally different. This is one of the limitations on the describability of crochet and knitting using the same terms — but also provides fuel for additional posts.